180:1 Mini Plastic Gearmotor, 90° 3mm D-Shaft Output

This compact, inexpensive plastic gearmotor (brushed DC motor with a 180:1 reduction gearbox) is well suited for use in small robots. While intended for operation at 4.5 V, it should run comfortably in the 3 V to 6 V range. The gearbox has a 9.7mm-long, 3 mm-diameter D-shaped output shaft that is perpendicular to the motor shaft, and a built-in safety clutch helps protect the gears from excessive loads.